TROUBLESHOOTING
9-1
EAM20148
TROUBLESHOOTING
EAM30309
GENERAL INFORMATION
TIP
Troubleshooting information provided here does not cover all the trouble symptoms, possible causes,
and remedial actions. Some items may not apply depending on the model. Use this information as a
guide and quick reference matrix when performing basic troubleshooting. Refer to the each chapter for
detailed information on checking, adjustment, and replacement.
EAM30509
TROUBLESHOOTING OF ENGINE (fault code not detected)
TIP
If a fault code is detected, refer to the “FUEL INJECTION SYSTEM” on page 8-17.
Engine does not crank.
Engine will not start or is difficult to start, but it cranks.
Symptom
Possible cause
Actions
Starter motor does not operate
Refer to “TROUBLESHOOTING” under “ELECTRIC STARTING
Starter motor operates, but the
engine does not crank.
Starter clutch malfunction
Replace the starter clutch.
Improper oil grade (starter clutch
slipping)
Change to recommended engine
oil.
Stuck piston or seized crankshaft
Disassemble and check the
engine. Replace defective parts.
Symptom
Possible cause
Actions
Spark plug does not produce a
spark
Refer to “TROUBLESHOOTING” under “IGNITION SYSTEM” on page
Fuel not supplied
—
Measure the fuel pressure.
Empty fuel tank
Fill the fuel tank with fuel.
Clogged fuel tank cap breather
hole
Clean the fuel tank cap.
Clogged or damaged fuel hose
Clean, repair, or replace the fuel
hose.
Fuel leakage
Check the fuel passage. Repair or
replace as necessary.
Clogged fuel pump
Clean or replace the fuel pump.
Cracks or damage in fuel pump
Replace the fuel pump.
Fuel pump malfunction
Refer to “TROUBLESHOOTING”
Failed or clogged fuel injector
Replace the fuel injector.
ECU failure
Replace the ECU.
Summary of Contents for YZ250FX 2021
Page 6: ...EAM20162 YAMAHA MOTOR CORPORATION U S A YZ MOTORCYCLE LIMITED WARRANTY ...
Page 10: ......
Page 61: ...TIGHTENING TORQUES 2 16 ...
Page 62: ...CABLE ROUTING DIAGRAM 2 17 EAM20152 CABLE ROUTING DIAGRAM Frame and engine left side view ...
Page 64: ...CABLE ROUTING DIAGRAM 2 19 Frame and engine right side view ...
Page 66: ...CABLE ROUTING DIAGRAM 2 21 Handlebar front view ...
Page 68: ...CABLE ROUTING DIAGRAM 2 23 Frame and engine top view ...
Page 70: ...CABLE ROUTING DIAGRAM 2 25 Frame and battery top view ...
Page 72: ...CABLE ROUTING DIAGRAM 2 27 Rear brake right side view ...
Page 74: ...CABLE ROUTING DIAGRAM 2 29 ...
Page 112: ...ELECTRICAL SYSTEM 3 36 ...
Page 153: ...HANDLEBAR 4 39 Throttle grip free play 3 0 6 0 mm 0 12 0 24 in ...
Page 166: ...FRONT FORK 4 52 1 ...
Page 184: ...CHAIN DRIVE 4 70 ...
Page 189: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 3 1 Oil filter element 2 Oil pump ...
Page 190: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 4 1 Intake camshaft 2 Exhaust camshaft ...
Page 264: ...TRANSMISSION 5 78 ...
Page 274: ...WATER PUMP 6 9 ...
Page 284: ...THROTTLE BODY 7 9 ...
Page 287: ......
Page 288: ...IGNITION SYSTEM 8 1 EAM20142 IGNITION SYSTEM EAM30277 CIRCUIT DIAGRAM ...
Page 292: ...ELECTRIC STARTING SYSTEM 8 5 EAM20143 ELECTRIC STARTING SYSTEM EAM30279 CIRCUIT DIAGRAM ...
Page 296: ...CHARGING SYSTEM 8 9 EAM20144 CHARGING SYSTEM EAM30282 CIRCUIT DIAGRAM ...
Page 299: ...CHARGING SYSTEM 8 12 ...
Page 300: ...SIGNALING SYSTEM 8 13 EAM20154 SIGNALING SYSTEM EAM30348 CIRCUIT DIAGRAM ...
Page 304: ...FUEL INJECTION SYSTEM 8 17 EAM20145 FUEL INJECTION SYSTEM EAM30284 CIRCUIT DIAGRAM ...
Page 329: ...FUEL INJECTION SYSTEM 8 42 ...
Page 330: ...FUEL PUMP SYSTEM 8 43 EAM20146 FUEL PUMP SYSTEM EAM30287 CIRCUIT DIAGRAM ...
Page 362: ...SELF DIAGNOSTIC FUNCTION AND DIAGNOSTIC CODE TABLE 9 15 ...
Page 372: ...CHASSIS 10 9 ...
Page 374: ......
Page 376: ......
Page 377: ...YZ250FXM 2021 WIRING DIAGRAM BAJ 2819U 11_WD indd 1 2020 06 29 15 46 05 ...
Page 378: ...YZ250FXM 2021 WIRING DIAGRAM BAJ 2819U 11_WD indd 2 2020 06 29 15 46 06 ...